The present invention generally relates to a bus bar blank, bus bars formed from the bus bar blank and a branch joint box including the bus bars and more particularly, to bus bars mounted in a branch joint box, in which bus bars of a plurality of patterns can be formed from one kind of a bus bar blank molded from an identical die and a branch joint box in which the bus bars of one pattern formed from the bus bar blank are mounted such that efficiency for assembling the branch joint box is raised.
Conventionally, a plurality of kinds of bus bars are accommodated in a branch joint box which is connected to intermediate portions of wiring harnesses for a motor vehicle. Shapes of these bus bars, i.e., bus bar patterns vary according to circuit configuration. When the bus bar patterns are different from each other, the bus bar blanks have hitherto been molded by different dies. Therefore, when there are a number of kinds of the bus bar patterns, a number of kinds of dies are also required to be prepared, thereby resulting in rise of production cost. When the bus bars are mounted on the branch joint box, the bus bars having different shapes are required to be attached to predetermined locations, respectively and thus, assembly of the branch joint box is troublesome.
Meanwhile, in the branch joint box, a branch joint point is concentrated at one spot so as to perform branch joint of wires reasonably and economically. In response to recent rise of density of wiring harnesses, branch joint boxes having various kinds of shapes are known.
For example, Japanese Utility Model Laid-Open Publication No. 4-131117 (1992) filed by the assignee assigned by the present inventors discloses a branch joint box shown in FIGS. 1 to 3. In this known branch joint box, a casing 73 is formed by upper and lower casings 71 and 72 which are formed with connection openings 71a and 72a for a connector X, respectively. A bus bar 74 is disposed between the upper and lower casings 71 and 72. The bus bar 74 includes an elongated base portion 74a and a plurality of pairs of tabs 74b arranged at a predetermined interval in a longitudinal direction of the base portion 74a and extending from opposite sides of the base portion 74a such that the tabs 74b project into the connection openings 71a and 72a.
The upper and lower casings 71 and 72 are of identical shape. On upper and lower faces of the casing 73, the connection openings 71a and 72a are formed symmetrically. Hence, in this known branch joint box, even if the connector X is connected to either one of the connection openings 71a and 72a of the upper and lower casings 71 and 72, an identical branch circuit is formed. As a result, the connector X can be connected to the known branch joint box without the need for paying attention to the upper and lower faces of the casing 73.
However, the known branch joint box referred to above is structurally complicated because the casing 73 is formed by two members, i.e., the upper and lower casings 71 and 72. Meanwhile, since the upper and lower casings 71 and 72 are molded by resin separately, resinous molding of the upper and lower casings 71 and 72 should be performed a total of two times, thereby resulting in rise of production cost. Furthermore, in the known branch joint box, a case in which the upper and lower casings 71 and 72 have different shapes, respectively may happen. In this case, two kinds of dies are required to be prepared, thereby resulting in further rise of production cost due to increase of cost for the dies.